Nigeria’s Minister of Petroleum Resources Diezani Alison-Madueke gestures as he speaks during a session at the World Economic Forum in Davos, Switzerland, Friday, Jan. 27, 2012.

Nigeria’s former oil minister has been arrested in London, the BBC said on Friday quoting unnamed family members, after Britain’s National Crime Agency said it had detained five people over alleged international corruption.

The identities and nationalities of those held were not disclosed but the broadcaster said on its website that relatives of Diezani Alison-Madueke confirmed she had been arrested in the British capital.

Alison-Madueke was Nigeria’s minister of petroleum resources from 2010 until earlier this year when Muhammadu Buhari defeated Goodluck Jonathan in presidential polls.

She was the first woman to hold the post in Nigeria, Africa’s number one crude producer, and the first female president of the global oil cartel OPEC.

Britain’s NCA, which investigates serious and organized crime, said in a statement on its website that its international corruption unit arrested five people across London.

The arrests were “part of an investigation into suspected bribery and money-laundering offences”, it added.

No further details were given but Nigerian media reported that Alison-Madueke was granted bail but had her passport seized and was ordered to stay at her London address.

The 59-year-old, a close ally of Jonathan whose administration was dogged by allegations of corruption, has faced accusations of graft in the past but denied wrong-doing.

Buhari, who was elected on an anti-corruption ticket, has pledged to crack down on endemic fraud in government and state-run agencies, in particular in the oil sector.

He has said that “mind-boggling” sums have been stolen over the years and promised to prosecute those responsible.

But he has also said he would not conduct a witch-hunt against the former administration.

No one was immediately available for comment at Nigeria’s Economic and Financial Crimes Commission (EFCC) when contacted by AFP and the government in Abuja said it had “no information” on the arrests.

Online and social media reports, however, said the EFCC had sealed Alison-Madueke’s home in the capital, Abuja.

Alison-Madueke has reportedly been overseas since Buhari came to power on May 29.